Explosive train barrier module for fuzes

ABSTRACT

A mechanical barrier module is provided between the primary and secondary explosives of an explosive train. The barrier module is fabricated from a single block having integral interlocking sections defined by through-molded slots and interconnecting shear points. Explosive motor means are provided for each interlocking section to facilitate the shearing of said shear points and release of said interlocking sections. The respective sections are interlocked in such a manner that the mutual release of all of said sections can only result by the release of said sections in one predetermined sequence. Detonation means are provided for detonating the secondary explosive when all of said interlocking sections are released.

United States Patent 91 Overman [llj 3,760,726

[ 1 Sept. 25, 1973 EXPLOSIVE TRAIN BARRIER MODUL FOR FUZES [75] Inventor: David L. Overman, Beltsville, Md.

[73 Assignee: The United States of America as represented by the Secretary of the Army.

[22] Filed: Mar. 9, 1972 [21] App]. No.: 233,195

[52] US. Cl. 102/22, 102/27 R, 102/70 R, 102/76 R [51] Int. Cl. F42b 3/10 [58] Field of Search 102/768l.6,

[56] References Cited UNITED STATES PATENTS 2,969,737 l/l96l Bild 102/78 X 2,918,870 12/1959 Meister 102/81 X 2,830,539 4/1958 Cecil Jr...

Primary Examiner-Samuel W. Engle v Atzorneyl-larry M. Saragovitz et al.

[57] ABSTRACT A mechanical barrier module is provided between the primary and secondary explosives of an explosive train.

.The barrier module is fabricated from a single block having integral interlocking sections defined by through-molded slots and interconnecting shear points. Explosive motor means are provided for each interlocking section to facilitate the shearing of said shear points and release of said interlocking sections. The respective sections are interlocked in such a manner that the mutual release of all of said sections can only result by the release of said sections in one predetermined sequence. Detonation means are provided for detonating the secondary explosive when all of said interlocking sections are released.

9 Claims, 3 Drawing Figures EXPLOSIVE TRAIN BARRIER MODULE FOR FUZES RIGHTS OF GOVERNMENT The invention described herein may be manufactured, used and licensed by or for the Government of the United States, for governmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF INVENTION 1. Field of the Invention The present invention relates to means for providing interruption between the primary and secondary explosives of safety and arming devices for fuzes used with all ordnance munitions.

2. Description of Prior Art Prior art explosive train interruption devices have generally consisted of complex assemblies of movable, interlocking component parts. These barrier devices are often expensive to manufacture and of limited reliability or safety.

The barrier module of the present invention overcomes the disadvantages of the prior art by providing a mechanical logic device which can be manufactured at low cost with fully automated equipment and provides a high degree of safety for an explosive train.

SUMMARY OF INVENTION Accordingly, it is an object of the present invention to provide a mechanical logic device suitable for use as a barrier module in an explosive train.

It is another object of the present invention to provide a mechanical logic circuit which can be fabricated at a relatively low cost.

It is still another object of the present invention to provide a barrier module which can be made in very small sizes with essentially infinite flexibility of design.

It is a further object of the present invention to provide a mechanical barrier module in an explosive train which demonstrates a high degree of safety against actuation by accidental or unexpected inputs.

These and other objects of the invention are achieved by providing a mechanical logic system which can be fabricated from a single plastic block having integrally molded interlocking sections formed therein. The molded sections are defined by through-molded slots and interconnecting shear points. A plurality of explosive motors are provided for the respective molded sections to facilitate the shearing of said shear points and the movement of the interlocking sections from an interlocked position to a mutually released position.

In the embodiment shown, there are provided three interlocking molded sections or elements driven by three respective explosive motors. The three interlocking sections or elements coact in such a way that the movement of the same between an interlocked and released position can only occur in one predetermined sequence. This design facilitates a very high order of safety since the first, second and third motor must be actuated in a unique sequence in order to release said molded sections and arm the explosive train. Further safety is achieved by having the output detonator as the fourth element in the sequence.

In one embodiment, the barrier module of the present invention could be used in the explosive train of a gun fired projectile. In this instance a first motor and its associated molded section would be actuated by a signal from an acceleration sensor which could distinguish between velocity changes of .80 fps due to accidental drops and velocity changes of greater than fps due to actual firings. An example of such a sensor would be a solid state piezo-electric device. A second motor and its associated molded section would be actuated by a signal from a sensor which detects spin or air flow. A third motor and its associated molded section would be actuated by a time delay device to assure that the projectile has traveled a safe distance from the gun. The mechanical logic system of the present invention would only permit the sequential actuation of the first, second and third molded sections in that order. Therefore, the projectile could not be detonated unless it were fired at a speed greater than 160 fps; it had a proper spin velocity; and it had traveled a sufficient predetermined time.

A more complete appreciation of the invention and many of the attendant advantages thereof will become more apparent with reference to the following description when considered in connection with the accompanying drawings wherein:

FIG. 1 is an illustration of the integrally molded features of a typical embodiment of the barrier module block of the present invention.

FIG. 2 is a partial view in section of the barrier module block of FIG. 1 illustrating the nature of the explosive motor means inserted therein.

FIG. 3 is a partial view in section of the barrier module block in FIG. I illustrating the nature of the detonation means of the present invention.

DESCRIPTION OF A TYPICAL EMBODIMENT Referring to FIG. I there is provided a block 5 having many integrally formed features therein. The block 5 could be molded of plastic. However, other materials and fabrication techniques may be used without departing from the spirit and scope of this invention. The integrally molded features of the block comprise the mechanical logic system of this invention. The mechanical logic system includes three interlocking sections 6, 7 and 8 which are integrally molded in block 5. Block 5 is also provided with a plurality of through-molded slots 17. The first molded section 6 is defined by through-molded slots 17 and interconnecting shear points 9, 10, 11 and 12. The second molded section 7 is defined by through-molded slots 17 and interconnecting shear points I2, 19, 20 and 21. The third molded section is defined by through-molded slots 17 and shear points 25, 26, 27 and 28. Upon the shearing of the foregoing shear points the three molded sections become three separately movable elements, which are movable along three intersecting linear paths, as will become more apparent hereinafter.

Sections 6, 7 and 8 are shown in FIG. 1 in a first interlocked position. Molded section 6 is provided with a tongue 14 which fits into a notch 16 of molded section 7. Section 7 is provided with a hook portion 23 adjacent notch 16. The coaction of the tongue I4, notch 16 and hook 23 prohibit the movement of section 7, as long as the tongue 14 of section 6 remains in slot 16. Section 8 is disposed in juxtaposition to both sections 6 and 7 and movement thereof in the direction of sections 6 and 7 is prohibited by the abutment of surface 15 against section 6 and the coaction of tab 37 with notch 38 of section 7 until sections 6 and 7 are retracted to mutually released positions. In addition tab 37 and notch 38 prohibit the movement of section 7 subsequent to the movement of tab 37 on section 8 into notch 38. Section 8 is further provided with an integrally molded detent 33 for holding point 29 against point 30 which will become more apparent hereinafter.

Also illustrated in block of FIG. 1 are plurality cavities A, B and C for receiving first, second and third explosive motors or bridges. The cavities A, B, and C are arranged so that the motors therein will drive sections 6, 7 and 8, respectively, from the interlocked position shown to a position in which each section is mutually released. The cavities and associated motors are so disposed with respect to the sections 6 7 and 8, so that when each motor is energized the shearing of the respective shearing points is facilitated which releases sections 6, 7 and 8 for movement.

The block of FIG. 1 is further provided with throughmolded openings or cavities 13, 18 and 36. Opening 13 is disposed in alignment with molded section 6 so that upon energization of the first motor in cavity A shearing occurs at points 9, 10, 11 and 12 and section 6 is driven into opening 13. Opening 18 performs a similar function with respect to section 7. However, opening 18 also performs an additional function when section 7 is restrained from movement by section 6. For example, if the second motor in cavity B should be energized before the first motor in cavity A, section 6 will still be interlocked with section 7. Therefore, section 7 cannot be driven into opening 18 when the motor in cavity B is energized. In this instance opening 18 will act as a vent for the pressure generated by the explosion of the motor in cavity B. Opening 36 performs a similar venting function in the event that the third motor in cavity C is energized before either the first motor in Cavity A or the second motor in cavity B. In this instance the explosion in cavity C will fracture block 5 at 35 and the pressure of the explosion will be vented into opening 36.

In the embodiment shown, the motors or bridges in cavities A, B and C and the detonator 4 to be described hereinafter are identical in nature. Therefore, the motors and detonator are equally likely to fail from accidental or unexpected inputs. This coupled with the mechanical logic circuit of the present invention decreases the probability of failure of the barrier module of the present invention. The barrier module of this invention yields a safety failure rate of only one in 2.5 million even if each of the three explosive motors and detonator 4 have a safety failure rate of one in 18. The safety factor could be further increased by making the three motors less sensitive to heat, static and RF effects than the detonator 4.

FIG. 2 illustrates a partial sectional view taken through cavity C of barrier module block 5 sandwiched between a top plate 39 and a bottom plate 40. Plates 39 and 40 may also be fabricated from plastic and may be welded, glued, or snap-fitted to block 5. Tongue and groove arrangements 43 and 44 are provided as means for sealing the slider channels of members 6, 7 and 8 and for aligning top and bottom plates 43 and 44 with block 5. Plates 43 and 44 function to constrain the movement of sections or members 6, 7 and 8 to a plane within block 5. Top plate 39 has all three motors and detonator 4 (FIG. 3) mounted thereon for alignment with cavities A, B and C and relay charge or trigger means 31. Each motor and detonator 4 include a propellant charge 47 held in place by a plug 48. Top plate 39 can also function as a circuit board for use in detonating each respective explosive motor. As shown in FIG. 2 terminals 45 are provided for connection at one end to appropriate sensors (not shown) and at the other end to a conductive explosive composition 46.

Referring to FIG. 3, molded section 8 of block 5 is illustrated with relay charge or trigger means 31 in alignment with detonator 4 mounted in top plate 39 and a lead charge 32 mounted in bottom plate 40. This is the position that section 8 will occupy after section 6 and 7 are driven into openings 13 and 18 and the motor in cavity C has been energized. Lead charge 32 is disposed in a molded hole in bottom plate 40 which defines a thin bottom diaphram 41. The top of the hole in plate 40 is sealed with a sealant material or a thin welded membrane 42.

DESCRIPTION OF OPERATION The operation of the barrier module of the present invention will now be briefly described with reference to the accompanying drawings. The logic system of the present invention may be thought of as a lock with sections 6 and 7 defining tumblers thereof and section 8 functioning as a bolt. When the first motor in cavity A is energized or exploded the pressure generated will shear block 5 at points 9, 10, 11 and 12 and drive the tumbler or section 6 into opening 13. The tongue 14 on section 6 thereby withdraws from notch 16 in section 7 and releases it for movement when the second motor in cavity B is energized. The movement of section 6 into opening 13 also partially unblocks the path for movement of the section or bolt 8 at surface 15. Next upon energization of the second motor in cavity B block 5 will be sheared at points 19, 20 and 21 and section 7 will be driven into opening 18 due to the pressure of the explosion. This then provides a free path for movement of the bolt or section 8 since tumblers 6 and 7 are both retracted. Upon energization of the third motor in cavity C point 29 on the bolt or section 8 will be driven against point 30 or block 5. Section 8 will be held in place by integrally molded detent 33 in block 5. In this position the relay charge or trigger means 31 will be in alignment with detonator 4 and lead charge 32, which defines the armed position of the explosive train.

The sequence of operation of the sections 6, 7 and 8 and detonator 4 can only occur as described above in order to detonate the secondary explosive. If any of the motors or the detonator are energized out of sequence the final detonation cannot occur. For example if the second motor in cavity B is energized first, section 7 will be restrained from movement by the coaction of tongue 14' and notch 16. Likewise, if the third motor is energized first section 8 will be blocked by both sections 6 and 7. In addition tab 37 will be forced into notch 38 which will restrain future movement of section 7.

The present invention provides a barrier module concept that is safe, compact, rugged, and can be produced at very low cost on fully automated equipment. Although only a single design is shown for purposes of illustration, it is intended that this invention cover such modules that employ any of the following features: pivoting, rotary, sliding members or combinations thereof; members moving in the horizontal (as shown) or vertical planes or combinations thereof; modules employing cast parts, insert molded parts, sintered parts, propellant driven parts, cam driven parts, molded springs, integral linkages, hinges, shear sections, integral detents, and single or multislide moldings or castings; welded, adhesive bonded, or snap fitted parts; more or less than three pieces; and designs using logic which is more or less complicated than that illustrated. One example of additional logic other than the use of extra primary locking members is the use of time gates. That is, a secondary locking member that is driven so as to lock one or more of the primary members if the selected primary member does not function within a preset time after another member functions. For instance, the requirement could be added that section 8 must move within 500 milliseconds after the'section 6 moves or it will be locked out (prevented from arming) by the time gate. The time gate could be a separate slider whose drive motor is initiated by an electronic'or pyrotechnic delay.

It should be understood that the invention is not limited to the exact details of construction shown and described herein for obvious modifications will occur to persons skilled in the art.

What is claimed is:

1. An explosive train barrier module comprising:

a. a plurality of coacting mechanical locking means movable between a first interlocked position and a second mutually released position, said locking means being movable to said second mutually released position by movement of the respective locking means in only one predetermined sequence;

. a plurality of motor means for moving each respective locking means between said first interlocked position and said second mutually released position in response to signals received in accordance with said predetermined'sequence; and

c. means for detonating an explosive when said locking means occupies said second mutually released position,

d. wherein said respective locking means comprise integrally molded sections in a single block, said molded section being defined by through-molded slots and interconnecting shear points, said block further including a plurality of through-molded openings into which said molded sections may move to occupy said second mutually released position.

2. The invention according to claim 1, wherein said motor means comprise explosive charge means disposed in said block to facilitate the shearing of said shearing points and the movement of said respective molded sections into said second mutually released positions in response to the pressure generated by the actuation of the respective explosive charge means.

3. The invention according to claim ll, wherein said locking means comprises three of said molded sections, said sections being disposed for movement along three linear paths which intersect at a common point, first and second sections being retractable from said common point into said through-molded openings to occupy said second mutually released position, a third section movable toward said common point to occupy said mutually released position, said first section including means coacting with said second and third sections for restraining the movement of said second and third sections until said first section is moved into said mutually released position, said second section including means coacting with said third section for restraining movement of said third section until said second section is moved to said mutually released position and wherein means are provided in said third section for triggering said detonation means when said third section is moved to said mutually released position; whereby said explosive can only be detonated if said first, second and third sections are sequentially moved in that order.

4. The invention according to claim 3, wherein said motor means comprise an explosive charge means disposed in said block for each respective section to facilitate the shearing of said shearing points and the movement of said respective molded sections into said second mutually released positions in response to the pressure generated by the actuation of the respective explosive charge means.

5. The invention according to claim 3, wherein there is further provided coacting means between said second and third sections for restraining the movement of said sections, if said third section has previously been moved.

6. The invention according to claim 4, wherein there is further provided coacting means between said second and third sections for restraining the movement of said section, if said third section has previously been moved.

7. The invention according to claim 4, wherein said block is sandwiched between first and second plate means for constraining the movement of said molded sections in the plane of said block.

8. The invention according to claim 7, wherein said motor means are mounted on one of said plate means and said block contains cavities for receiving said motors.

9. The invention according to claim 7, wherein said means for detonating an explosive is disposed in one of said plates. 

1. An explosive train barrier module comprising: a. a plurality of coacting mechanical locking means movable between a first interlocked position and a second mutually released position, said locking means being movable to said second mutually released position by movement of the respective locking means in only one predetermined sequence; b. a plurality of motor means for moving each respective locking means between said first interlocked position and said second mutually released position in response to signals received in accordance with said predetermined sequence; and c. means for detonating an explosive when said locking means occupies said second mutually released position, d. Wherein said respective locking means comprise integrally molded sections in a single block, said molded section being defined by through-molded slots and interconnecting shear points, said block further including a plurality of throughmolded openings into which said molded sections may move to occupy said second mutually released position.
 2. The invention according to claim 1, wherein said motor means comprise explosive charge means disposed in said block to facilitate the shearing of said shearing points and the movement of said respective molded sections into said second mutually released positions in response to the pressure generated by the actuation of the respective explosive charge means.
 3. The invention according to claim 1, wherein said locking means comprises three of said molded sections, said sections being disposed for movement along three linear paths which intersect at a common point, first and second sections being retractable from said common point into said through-molded openings to occupy said second mutually released position, a third section movable toward said common point to occupy said mutually released position, said first section including means coacting with said second and third sections for restraining the movement of said second and third sections until said first section is moved into said mutually released position, said second section including means coacting with said third section for restraining movement of said third section until said second section is moved to said mutually released position and wherein means are provided in said third section for triggering said detonation means when said third section is moved to said mutually released position; whereby said explosive can only be detonated if said first, second and third sections are sequentially moved in that order.
 4. The invention according to claim 3, wherein said motor means comprise an explosive charge means disposed in said block for each respective section to facilitate the shearing of said shearing points and the movement of said respective molded sections into said second mutually released positions in response to the pressure generated by the actuation of the respective explosive charge means.
 5. The invention according to claim 3, wherein there is further provided coacting means between said second and third sections for restraining the movement of said sections, if said third section has previously been moved.
 6. The invention according to claim 4, wherein there is further provided coacting means between said second and third sections for restraining the movement of said section, if said third section has previously been moved.
 7. The invention according to claim 4, wherein said block is sandwiched between first and second plate means for constraining the movement of said molded sections in the plane of said block.
 8. The invention according to claim 7, wherein said motor means are mounted on one of said plate means and said block contains cavities for receiving said motors.
 9. The invention according to claim 7, wherein said means for detonating an explosive is disposed in one of said plates. 